How can one not forget tube amps? Well you can get them for youyr car (a solid/state /hybrid form). BK Butler started making them. Then Paze Audio , Then PPI, and now BK Butler is back at it with their "Blue" TubeDrivers"

This is going in my '73 Boattail:

http://img.photobucket.com/albums/v309/sicksteve/TubedriverTD450.jpg